Expose CEF web server API

[cztomczak]

Python has a built-in http.server (and SimpleHTTPServer in Python 2), however it is slow and single threaded according to [1]. So it would be useful to expose Chromium's built-in web server.

See cef_server.h API:

• CefServer: a web server that supports HTTP and WebSocket requests
• CefServerHandler

Upstream issue:
https://bitbucket.org/chromiumembedded/cef/issues/2278/expose-internal-http-websockets-server

See also a multi-threaded web server in Python based on simple http server [2].

Update Tutorial and its "Communication using http requests" sub-section.

Ref:
[1] https://stackoverflow.com/questions/12905426/what-is-a-faster-alternative-to-pythons-http-server-or-simplehttpserver
[2] https://stackoverflow.com/questions/14088294/multithreaded-web-server-in-python